/*
 * $Id: H264Nalu.cpp 1775 2010-04-02 19:28:08Z Spec-Chum $
 *
 * (C) 2006-2010 see AUTHORS
 *
 * This file is part of mplayerc.
 *
 * Mplayerc is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * Mplayerc is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "stdafx.h"
#include "H264Nalu.h"

void CH264Nalu::SetBuffer(BYTE* pBuffer, int nSize, int nNALSize)
{
    m_pBuffer		= pBuffer;
    m_nSize			= nSize;
    m_nNALSize		= nNALSize;
    m_nCurPos		= 0;
    m_nNextRTP		= 0;

    m_nNALStartPos	= 0;
    m_nNALDataPos	= 0;
}

bool CH264Nalu::MoveToNextStartcode()
{
    int		nBuffEnd = (m_nNextRTP > 0) ? min(m_nNextRTP, m_nSize - 4) : m_nSize - 4;

    for(int i = m_nCurPos; i < nBuffEnd; i++)
    {
        if((*((DWORD*)(m_pBuffer + i)) & 0x00FFFFFF) == 0x00010000)
        {
            // Find next AnnexB Nal
            m_nCurPos = i;
            return true;
        }
    }

    if((m_nNALSize != 0) && (m_nNextRTP < m_nSize))
    {
        m_nCurPos = m_nNextRTP;
        return true;
    }

    m_nCurPos = m_nSize;
    return false;
}

bool CH264Nalu::ReadNext()
{

    if(m_nCurPos >= m_nSize) return false;

    if((m_nNALSize != 0) && (m_nCurPos == m_nNextRTP))
    {
        // RTP Nalu type : (XX XX) XX XX NAL..., with XX XX XX XX or XX XX equal to NAL size
        m_nNALStartPos	= m_nCurPos;
        m_nNALDataPos	= m_nCurPos + m_nNALSize;
        int nTemp			= 0;
        for(int i = 0; i < m_nNALSize; i++)
        {
            nTemp = (nTemp << 8) + m_pBuffer[m_nCurPos++];
        }
        m_nNextRTP += nTemp + m_nNALSize;
        MoveToNextStartcode();
    }
    else
    {
        // Remove trailing bits
        while(m_pBuffer[m_nCurPos] == 0x00 && ((*((DWORD*)(m_pBuffer + m_nCurPos)) & 0x00FFFFFF) != 0x00010000))
            m_nCurPos++;

        // AnnexB Nalu : 00 00 01 NAL...
        m_nNALStartPos	= m_nCurPos;
        m_nCurPos	   += 3;
        m_nNALDataPos	= m_nCurPos;
        MoveToNextStartcode();
    }

    forbidden_bit		= (m_pBuffer[m_nNALDataPos] >> 7) & 1;
    nal_reference_idc	= (m_pBuffer[m_nNALDataPos] >> 5) & 3;
    nal_unit_type		= (NALU_TYPE)(m_pBuffer[m_nNALDataPos] & 0x1f);

    return true;
}